The invention relates to a chip module and to a data carrier with a chip module, the chip module having a holder means with holder means connecting layers and a chip with chip connecting layers, which connecting layers are connected to one another with the aid of bond wires, each chip connecting layer being provided with a wire connecting means whereto an end bonded in a wedge-shape fashion of a bond wire is connected.
A chip module as mentioned above is illustrated and described in Patent document EP 0 397 426 A2. In the known chip module, an end bonded in a spherical fashion of a bond wire is provided on each chip connecting layer as wire connecting means; this is frequently called a xe2x80x9cnail bondxe2x80x9d in the technical language. In a plan view of the chip connecting layer on which the xe2x80x9cnail bondxe2x80x9d is provided, such a xe2x80x9cnail bondxe2x80x9d has a smaller dimension than the chip connecting layer lying under it. Furthermore, in a direction perpendicular to the chip connecting layer lying under it, such a xe2x80x9cnail bondxe2x80x9d has a relatively large dimension, that is to say a relatively large height. The small area of such a xe2x80x9cnail bondxe2x80x9d is attended by the problem that during the bonding operation in which the end bonded in a wedge-shape fashion of a bond wire is connected to the xe2x80x9cnail bondxe2x80x9d, the bond wire has to be fed very precisely to the xe2x80x9cnail bondxe2x80x9d, in order to ensure that the connection is made reliably. The large height of such a xe2x80x9cnail bondxe2x80x9d unfortunately has an unfavorable influence on the overall height of the chip module or of the data carrier containing the chip module, which data carrier can be formed, for example, by embedding the chip module in a plastic sleeve as mentioned in Patent document EP 0 397 426 A2. The fabrication of such a xe2x80x9cnail bondxe2x80x9d entails a relatively long period for the wire bonding method, because such a xe2x80x9cnail bondxe2x80x9d must be fabricated in the course of the wire bonding method.
It is an object of the invention to avoid the described drawbacks and to implement an improved chip module and an improved data carrier with such a chip module.
In order to achieve the object set forth above, inventive features are provided to a chip module in accordance with the invention such that a chip module in accordance with the invention can be characterized as follows:
a chip module with a holder means and with a chip connected to the holder means, where the chip has at least one chip connecting layer, and where the holder means has at least one holder means connecting layer, and where an associated wire connecting means is provided on the chip connecting layer, and where the wire connecting means and the holder means connecting layer are connected to one another with the aid of a bond wire, and where the bond wire has a bonded first end and a second end bonded in a wedge-shape fashion, and where the bonded first end is connected to the holder means connecting layer and the second end bonded in a wedge-shape fashion is connected to the wire connecting means, and where a flat metal layer extending parallel to the chip connecting layer is provided as the wire connecting means.
In order to achieve the object set forth above, inventive features are provided to a data carrier in accordance with the invention such that a data carrier in accordance with the invention can be characterized as follows:
a data carrier with a chip module with a holder means and with a chip connected to the holder means, where the chip has at least one chip connecting layer, and where the holder means has at least one holder means connecting layer, and where an associated wire connecting means is provided on the chip connecting layer, and where the wire connecting means and the holder means connecting layer are connected to one another with the aid of a bond wire, and where the bond wire has a bonded first end and a second end bonded in a wedge-shape fashion, and where the bonded first end is connected to the holder means connecting layer and the second end bonded in a wedge-shape fashion is connected to the wire connecting means, and where a flat metal layer extending parallel to the chip connecting layer is provided as the wire connecting means.
Because of the provision of the features in accordance with the invention it is achieved in a structurally simple and suitably reproducible manner, that the wedge-shape bond to be fabricated between an end, to be bonded in a wedge-shape fashion, of the bond wire and a wire connecting means can be fabricated with far less precision with regard to feeding the bond wire to the metal layer provided as the wire connecting means than in the case of the known solution described above. Furthermore, as a result of the steps taken according to the invention each wire connecting means takes up significantly less space in a direction perpendicular to the chip connecting layer lying under a wire connecting means than in the case of the known prior art described above. In a chip module in accordance with the invention, and in a data carrier in accordance with the invention, there is, moreover, the advantage that each wire connecting means can be fabricated by way of a method which is independent of the wire bonding method, and is carried out before the wire bonding method, thus offering the advantage that the wire bonding method can be carried out in a substantially shorter period of time than in the case of fabrication of the known chip module described above; consequently the so-called throughput or step duration in the manufacture of a chip module can be shortened substantially in accordance with the invention by comparison with the known method.
In a chip module in accordance with the invention and in a data carrier in accordance with the invention, the metal layer provided on a chip connecting layer can, given an appropriately sized area of the chip connecting layer, cover only a part of the chip connecting layer and in so doing nevertheless take up a sufficiently large area which ensures no complications in feeding the end to be bonded in a wedge-shape fashion to the metal layer provided as the wire connecting means. However, it has proved to be particularly advantageous when the features in accordance with claim 2 or claim 5 are provided in addition. The largest possible area is thus advantageously achieved for the metal layer which additionally also further fulfills a protective function for the entire chip connecting layer.
In a chip module in accordance with the invention and in a data carrier in accordance with the invention, each metal layer provided as the wire connecting means can consist of silver or tin. However, it has proved to be particularly advantageous when each metal layer provided as the wire connecting means consists of gold.
The aspects set forth above and further aspects of the invention emerge from the exemplary embodiments described below and are explained with the aid of these exemplary embodiments.